Slide block control means for radial piston machines

ABSTRACT

A radial piston machine wherein the slide block is movable radially of the cylinder block to thereby change the strokes of pistons in the cylinder bores of the cylinder block by means of a control system which employs a differential piston mounted in the housing for the cylinder block so as to be movable axially in parallelism with one end face of the slide block. The means for transmitting motion from the differential piston to the slide block constitutes a pin which is secured to the differential piston and extends into an endless groove in the one end face of the slide block or a lever which is pivotably mounted in the housing and is pivoted by the differential piston to thereby change the radial position of the slide block by way of a Ushaped entraining element. During radial movement, the slide block rolls along one of two parallel internal guide surfaces of the housing. Two rotary piston machines can be mounted adjacent and in mirror symmetry with respect to each other and their cylinder blocks can be driven by or drive a single shaft which is connected with one of the cylinder blocks in such a way that the respective housing can be pivoted away from the other housing.

[4 Oct. 21, 1975 SLIDE BLOCK CONTROL MEANS FOR RADIAL PISTON MACHINES [75] Inventor: Paul Bosch, Ludwigsburg, Germany [73] Assignee: Robert Bosch GmbH, Stuttgart,

Germany 22 Filed: July 19,1973

21 Appl. No.: 380,752

[30] Foreign Application Priority Data 7 Aug, 8, 1972 Germany 2238952 [52] US. Cl 91/497; 92/121 [51] Int. Cl. FDIB 13/06 [58] Field of Search 91/472, 485, 4 92, 497, 91/498 [56] References Cited UNITED STATES PATENTS 2,186,556 1/1940 Robbins 91/497 2,254,103 8/1941 Douglas 91/498 2,349,280 5/1944 Joy 91/485 2,373,449 4/1945 Benedek 92/12.1 3,194,171 7/1965 Ohligs 91/472 3,225,701 12/1965 Griffith 91/496 3,744,379 3/1971 Lucas 91/497 3,805,675 6/1970 Ecckmann 91/497 FOREIGN PATENTS OR APPLICATIONS 536,961 6/ 1941 United Kingdom 91/497 96,221 3/1921 Switzerland 91/497 6/1912 Germany ..91/492 2/1951 France ..91/497 Primary Examiner-William L. Freeh Attorney, Agent, or FirmMichael S. Striker [57] ABSTRACT A radial piston machine wherein the slide block is movable radially of the cylinder block to thereby change the strokes of pistons in the cylinder bores of the cylinder block by means of a control system which employs a differential piston mounted in the housing for the cylinder block so as to be movable axially in parallelism with one end face of the slide block. The means for transmitting motion from the differential piston to the slide block constitutes a pin which is secured to the differential piston and extends into an endless groove in the one end face 'of the slide block or a lever which is pivotably mounted in the housing and is pivoted by the differential piston to thereby change the radial position of the slide block by way of a U-shaped entraining element. During radial movement, the slide block rolls along one of two parallel internal guide surfaces of the housing. Two rotary piston machines can be mounted adjacent and in mirror symmetry with respect to each other and their cylinder blocks can be driven by or drive a single shaft which is connected with one of the cylinder blocks in such a way that the respective housing can be pivoted away from the other housing.

16 Claims, 6 Drawing Figures US. Patent 0a. 21, 1975 Sheet 1 of3 3,913,45

Fig.1 3 1 2 US. Patent Oct. 21, 1975 Sheet 2 of3 3,913,456

U.S. Patent Oct. 21, 1975 Sheet 3 of3 3,913,456

Fig.5

.-quired by conventional control means.

SLIDE BLOCK CONTROL MEANS FOR RADIAL PISTON MACHINES BACKGROUND 70F THE INVENTION It is already known to-move the slide block relative to the cylinder block to thereby change a' characteristic of the fluid stream flowing into and from the radial piston machine by resorting to two pistons which are mounted in the housing of the radial piston machine in such a way that one thereof is located diametrically op-:

posite the other with reference to the axis of the cusftomary pintle on which the'cylinder block rotates. A v drawback of such control systems isthat they contrib- .ute excessively to thedimensions'of the radial piston machine, especially as consideredradially of-the cylinde'r block. This is'highly undesirable,'especially in view chine occupies a relatively large amount of space, as

considered in the radial direction of thecylinder block and pintle. Therefore, such radial piston machines carinot be used as pumps or motors in many instances where they could be employed with considerable advantage if they would occupy less room.

SUMMARY E THE INvENT oN An object of the invention is to providea novel and improved radial piston machine which can be used, either alone or in combination with a similar machine, as

- a superior substitute for'presently known "radial piston vthe position of the slide block relative to the cylinder block occupies only a fraction of the space which is re- A further object of the invention is to provide novel and improved control means for moving the slide block appreciably beyond the slide block, as-considered in,

the radial direction of the cylinder block.

The invention is embodied in an arrangement which includes one or more radial piston machines and wherein each radial piston machine comprises a housing; a cylinder block rotatably mounted in; the housing and having a plurality of preferably equidistant radial cylinder bores, pistons which are reciprocably installed in the cylinder-bores and extend radially outwardly from'the cylinder block (each piston may be provided with a swivelling shoe which extends'radially beyond the cylinder block), and an annular slide block surrounding the cylinder block with clearance and being movable radially or substantially radially of the cylinder-block to thereby change the strokes of the" pistons and hence at least'one characteristicof the fluid stream which flows into and'from the housing when the cylinder block rotates relative to astationary pintle which is secured to the housingandhas high-pressure and low-pressure chambers located adjacent to the path'of the inner end portions of 'cylinder bores in the cylinder In accordance with a feature of the invention, at least one of the radial" piston machines"comprises'novel and ,1 improved control means for moving the' slide blockrelative to the respective cylinder block. The control means comprises a displacing piston (preferably a differential piston) which is-movable axially in 'a further cylinder bore provided therefor ;in'the housing of the respective machine and motion transmitting means of the fact that, by its very nature, a radial piston ma= (such as a pin or-a lever) for moving the slide block relative to the cylinder block in response to axial-movementof the displacing pistonzln order to reduce the dimensions of the respective housing, the displacing piston is movable axially in substantial or exact parallelism with an end face of the slide block and is preferably adjacent to the end face. Such mounting of the displacing piston insures :that the control means need not extend appreciably beyond the slide block, as considered in the radial direction of the'cylinderblocki v The novel features which are considered as characteristic of the invention are-set'forth in particular in the appended claims. 'The'irnprove'd radial pistonmachine itself, however, both as to its construction and its mode of operation, together with additional feature'sand 'advantages thereof, will be best understood upon perusal of the following detaileddescription of certain specific embodiments with reference to the accompanying drawing. 1 f i I BRIEF DESCRIPTIO OF THED AWING 1 FIG. .1 is an axial sectional view of a radial piston machine wherein the control mean s' for the slide block'is constructed and assembled in accordance with a first embodiment of the invention;

FIG. 2 is a transverse sectional view of the'pintle of direction of arrows from the line lIII-of FIG. 1;

FIG; 3 is a fragmentary sectional view as seen in the direction of arrows from the line III-III of FIG. 1;

FIG. 4 is a fragmentary sectional view substantially as seen in the direction of arrows from the line'IV-IV of FIG. 5 is a fragmentary axial sectional view of a radial piston machine which embodies modified control 'means for the slide block; Y

FIG.'6 is a schematic elevational view of a twin radial piston machine which can embody the control means of FIGS. I and 3 or FIG-'5.

I DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. I, there is shown a radial pis-, ton machine which can beused as a pump or as a motor mal clearance by "a cylindrical intemal surface sur- -rounding'lthe axial bore of a cylinder block 7 having-a "set of "equidis'tantradially extending cylinder bores 8 forreciprocable pistons-9. Each piston9 is provided "lihe' head :28 is slidable in the bore 27-with minimal with aswiveling'shoe 10 which extends radially outi I wardlybeyond the cylinderblockTand engages the cylindrical internal surfaceflof an annular slide block 11 tial direction of the pintle and register withthesmallere diameter inner. end portions or ports 18.0fsuccessive:

cylinder bores 8 in the cylinder block 7 when the latter rotates on the pintle. The chambers14, 15 respectively bommunicatewith fluid-conveying channels 16, 1.7 of .the housing 1 by .way of substantially. kidney-shaped :holes 16., 1.7." (see FIG. :2); The channel 16 supplies hydraulic fluid toand the channel l7sconveyshydraulic fluid from the radial piston mac'hine,'.or vice =versa. As shown .in FlG'..:-:l, there is provided a gradual and smooth transition from the holes '16, 17- into the respective control chambers and 15.

One of then-control chambers 14,15 is a high-pressure chamber and the other control chamber is alowpressure chamber. .Each of ,the holes 16', 17" has a portionwhich extendsyin substantial-parallelism with the axis of the. cylinder block 7- and terminates at the lefthand axial end of the pintle 5, as viewed in FIG. 1. The holes 16'. 17 are preferably machined into the pintle 5 in'aecorda'ri c'e'with an electrochemical process.

The cylinderlblock 7 is rigid with a shaft 19 which drives the-cylinder block when the machine operates'as a .pump'fandis driven by the cylinder block when the machine operates as a motor. The right-hand end portion of the'shaft as viewed in FIG. '1, is provided with a flange 21. having torque transmitting claws 22 which engage complementary claws or extend into matching sockets at the right-hand axial end of the cylinder block 7. The shaft 19 extends through a bore of the housing-land. through an axial bore of the pintle 5. The refer'erice character 19a denotes an antifriction bearing which is provided for the shaft 19 in the housing 1 and isspaced apart from the flangeof the pintle 5 in .the recess=4. Y

The control means for the slide block 11 is installed =in partin an insert 25 which is received in a recess 24 of the housing 1. The inner end portion 27 of the recess 24 constitutes a cylinder bore for the cylindrical enlarged portion or head 28 of a displacing piston 29 here shown as a differential piston. The shank 30 of the differential piston 29 is slidably guided in the blind bore 31 of a cylindrical sleeve 26 of the insert 25. The axis :ofathe differential piston 29 is normalqto the common axis of the pintle 5, cylinder block 7 and shaft 19. The larger surface 32' of the head 28 faces a first chamber 32 which is defined by thehead 28and housing 1 and constitutes the innermost portion of the cylinder bore 27.The' smaller surface 33 of the head 28 is adjacent to an annular second chamber 33 extending between the surface 33' and the inner end face of the sleeve 26.

clearance. The insert 25 can be considered as constituting a component part of the housing 1.

The shank30 of the differential piston 29 is provided withaa diametrically extending bore 34 for a motion transmitting pin35 which is rotatablein the bore 34 and whose axisis normal to the axis of .the shank 30. A

'projection 36'of the motion-transmitting pin 35 extends into an endlesscircular groove 37 machined into one end face 38 ofwthe slide block 11. The recess 24. is rather closely adjacent to the end .face 38 and the insert 25 projects only slightly beyondtheouter end of the recess 24 so that it does not contribute appreciably the the dimensions of the machine, as considered inthe radial direction ofthe cylinder block 7.

Additional details .of-the control means for the slide block 11, andmoreparticularly the regulating means for moving the differential piston 29 axially in parallelsurfaces 64, 65, 66 which are slidable in. the bore 48 of ism.with:the end face. 38 of the slide block, are illustrated in FIG. 3. The insert 25 is formed with abore 39 whose axis is parallel to the axis of the differential piston 29. The bore 39 receives a. portion of a reciprocable plunger 40. The plane including the axes of the differential piston 29 and the plunger 40 is normal to the axis of the shaft19 (not. shown in FIG. 3). The plunger 40 carries apivot member 41 for a two-armed lever 42 having a. shorter-arm .43 and a longer arm 45. The shorter arm 43. extends into a transverse groove or notch 44.which is machined into the periphery of the shank 30. The rounded endof the. arm 45 extends into a diametrically extending slot 46 provided therefor in a control'pistori 47. The control piston 47 is reciprocable in abore-48 machined into the insert 25 adjacent to the plunger 40 and having an axis located in the commonplane of the axes of the shank 30 and bore 39.

1 The .outerend portion- 50 oftheplunger 40'constitutes a hollow cylinder and the plunger 40 has an inter:

-nalchamber 51 including-a larger-diameter portion 52 in the end portion 50 and a smaller-diameterportion 62 in the adjacent (median) portion of the plunger 40. The portion 52;..of the .chamber 51 receives ,a first disksha'ped retainer 54 which normally abuts against an internal shoulder 53 of the portion 50, a second diskshaped retainer 56 which normally abuts against a stop here shown as a.split ring received in an internal groove of the end portion50, and resili'entmeans in the form of a helical spring 57 which is disposed between the retainers 54, 5 6. A shifter member 58 is connected with a bolt-6l whose .stem extends through coaxial holes 59, 60 of the retainers 54, 56. The shifter member 58 extends from the end portion 50 of the plunger 40 and isarticulately connected with a shifter lever 63 .which is accessible to the operator. The head of the bolt61 extends into the smaller-diameter portion 62 of thecharnberSl in the plunger40.

Thecontrol piston 47 has h ree cylindrical peripheral the insert 25. and an end face 67 engaged by one end convolution of a-helical spring68 which reacts against an internalannular shoulderof the insert 25 and urges the control piston 47 upwardly, as viewed in H6. 3. The end face 67 of the control piston 47 is further acted upon by hydraulic fluid which is admitted into the bore'48 by a conduit 69 connected to the highpressure outlet .-line 70 of the radial. piston machine (which is assumed to operate as a pump). The conduit 69 receives fluid from the-outletline 70 by way of a flow restrictor 71. The other end face 72*of the control piston 47 is subjected to-the full pressure of fluid in the outlet line 70 by way of a conduit 73. It will be noted that the conduits 69 and 73 respectively communicate with the outlet line 70 downstream and upstream of the flow restrictor 71. The space 75 surrounding an annular groove 74 of the control piston 47 between the cylindrical surfaces 65 and 66 communicates with a tank 77 by way of a conduit 76. The interior of the tank 77 is maintained atatmospheric pressure. 1

The insert 25 has an annular groove 78 whichcan communicate with the bore 48 but is sealed from'the latter by the cylindrical surface 65 of the control piston 47 when the latterassumes the neutral position shown in FIG. 3. A second annular groove 80 of the control piston 47 betweenthe cylindrical surfaces 64, 65 is surrounded by a space 79 and communicates with the an- -nular chamber 33 by way ofa bore 81' in the insert 25.

The space 79 further communicates with the outlet line 70 of the radial piston machine by way of a conduit 81. Thus, the pressure in the chamber 33 equals the'pressure of fluid in the outlet line 70. I

The housing 1 of the radial piston machine carries the body 82 of a fluid flow rate regulating valve 82 (hereinafter called metering valve). The body 82 has a blind bore 84 the open end of which is sealed by a threaded plug 83 and which receives with minimal clearance a reciprocable cylinder valve member 85. A chamber 88 between the lower end face 86 of the valve member'85 and the bottom surface 87 in the blind bore 84 receives ahelical spring 89 which biases the valve member 85 toward the plug 83. A second chamber 91 between the plug 83 and the upper end face 90 of the valve member 85 receives a second helical spring 92. The chambers 88 and9l communicate with each other by way of an axial bore 94 of the valve member 85. The median portion 93 of the bore 94 has a reduced diameter and constitutes a flow restrictor. The chamber 91 is in communication with the chamber 32 above the head 28 of the differential piston 29 byway of a channel 96. When the valve member 85 assumes a neutral position, its upper portion throttles the flow of fluid between the chamber 91"and channel 96. The lower chamber 88 is connected with the groove 78 by a further channel 95. The lower portion of the valve member 85 partially obstructs the flow of fluid between thechamber 88 and channel 95 when the valve member 85 assumes its neutral position.

The manner in which the-slide block 11 is mounted in the housing 1 'is illustrated in FIG. 4. The housing 1 has a flat internal guide surface 97 which is parallel to the axis of the differential piston 29 and to a second internal guide surface (not shown). The slide block 11 is disposed between the two guide surfaces in such a way whereby the spring 57 stores energy and causes the re- I tainer 54 to bear against the shoulder 53 so that the plunger 40 penetrates deeper into the bore 39 of the insert 25. The differential piston 29 is assumed to dwell in its neutral or idle position so that the arm 43 cannot move lengthwise of the sleeve 26. Consequently, as the plunger 40 penetrates deeper into the bore 39, the lever 42 pivots counterclockwise about the free end of the arm 43 in the transverse groove 44 of the shank 30 whereby the arm 45 of the lever 42 movesthe control piston 47 upwardly, as viewed in FIG. 3 to reduce the stress upon the resilient element 68. The outlet of the conduit 81 remains in communication with the space 79 between the cylindrical surfaces 65 and 64 of the control piston 47, i.e., the surface 65 does not obstruct the flow of fluid from the outlet line 70, through the conduit 81 and into the space 79 so that the pressure of fluid in the chamber 33 below the head 28 of the differential piston 29 continues to match the pressure of fluid at the outlet of the radial piston machine. As the control piston 47 moves upwardly, its cylindrical surface 65 allows the groove 78 to communicate with the space whereby the fluid can flow from the chamber 32 above the head 28 of the differential piston 29 by way of the channel 96, chamber 91, axial bore 94 of the valve member 85, chamber 88, channel 95, space 75 and conduit 76 which discharges into the tank 77.

chamber 91. This reduces the raterof outflow of fluid from the chamber 32 and hence the speed of the differential piston 29. The shank 30 entrains the motion transmitting pin 35 which, in turn, changes the position of the slide block 11 relative to the cylinder block 7. The slide block 11 rolls along one of the guide surfaces 97 in the housing 1. The eccentricity of the slide block 11 increases so that the volume of the fluid which is displaced by the pistons 9 also increases.

As the differential piston 29 moves relative to the insert 25, the lever 42 pivots about the axis of the member 41 (because the plunger 40 is then at a standstill) whereby the arm 45 displaces the control piston 47 against the opposition of the resilient element 68 so that the control piston reassumes its neutral position. The cylindrical surface 65 seals the groove 78 from the spaces 74 and 79 to interrupt the outflow of fluid from the chamber 32. This terminates the inward movement of the differential piston 29.

If the shifter lever 63 is moved in a counterclockwise direction, as viewed in FIG. 3, the shifter member 58 causes the bolt 61 to move downwardly so that the re tainer 54 bears against the spring 57 and the plunger 40 moves outwardly. The plunger 40 thereby pivots the lever 42 about the free end of the arm 43 in the groove 44 of the shank 30 (the differential piston 29 is stationary) so that the lever 42 pivots clockwise and its arm 45 causes the control piston 47 to move downwardly and to thereby stress the resilient element 68. The cylindrical surface 65 of the control piston 47 allows fluid to flow' between the space 79 andthe annular groove 78 so that the chamber 32 above the head 28 of the differential piston 29 is connected-with the outlet line 70 by'way of the channel 95, chamber 88, bore 94 of the .valve member 85, chamber 91 and channel 96. Since the area of the'surface 32 exceeds the area of the sur face 33 on the head 28, the differential piston 29 moves downwardly, as viewed in- FIG. 3, whereby the head 28ex'pels fluid from the chamber 33 by way of the bore 81, channel 95, chamber 88, bore 94 of the valve member 85, chamber 91 and channel '96. Thus, the

.fluid simply flows from the chamber 33 into the chamber 32. The speed of axial movement of the differential piston 29 is again regulated by the valve member 85 due'to a pressure differential-between the ends of the flow restrictor 93 in the bore 94.

smaller quantities of fluid.

The differential piston 29 further pivots the lever 42 .The other arm 114 of .the lever 110 is coupled to a U-shaped entraining element 116 by means of a pivot pin 115.-The entraining element 116 has two claws 116a which ent'endinto annular grooves 103a provided counterclockwise about the pivot member 41 (the v plunger is at a standstill). The arm 45 thereby gradually shifts the control plunger 47 so that the cylindrical surface seals the groove 78 from the spaces and 79. This terminates the axial movement of the differential piston 29 because the flow of fluid from the chamber 33 into' the chamber 32 is interrupted.

It will be noted that the control means of FIGS. 1 and 3 is a follow-up control means.

The radial piston rnachine of FIG. comprises moditied means fortransmitting motion from the displacing piston 107 to the annular slide block 103. The housing of the radial piston machine is provided with an'internal space 102 which receives the annular slide block 103in such a way that one end face of the slide block is adjacent to a surface 101 of the housing 100. The housing 100 is further provided with a recess 104 for an insert 105 having a sleeve-like portion 105a for the shank 106 of the displacing piston 107 which again constitutes a differential piston. The outer end portion of the insert 105 extends only slightly beyond the adjacent portion of the peripheral surface of the housing 100. This contributes to compactness of the radial piston machine. The insert 105 can be considered as forming part of the housing 100.

108 for a two-armed motion-transmitting lever replacing the pin 35 of FIG. 3. The motion-transmitting lever 110 is tumable about the axis of a pivot member 109 which is mounted in the housing 100. The effective lengths of both arms 111, 114 of the lever 110 are the same. The arm 1 11 extends through the cutout 108 and through a cutout 112 of the sleeve 105a and has an elongated slot 118 for a pin 113 of the shank 106. To this end, the shank 106 has a diametrically extending slot 106a-and the pin 113 extends across the slot 106a. The pin .113 has two flats and is tumable in the shank v106 so as toenable the motion transmitting lever 110 to pivot when the differential piston 107 moves axially.

The slot 118 thereby moves lengthwise along the flats of-the pin 113.

' in the respective endfaces of the slide block 103. It will be noted that the entraining element 1 16 is movable axially of the slide block 103 butis mounted thereon without'any or with negligible freedom of radial movement. This insures that the eccentricity of the slide block 103 relative-to the cylinder'blo'ck (not shown) changes when the differential piston 107 moves axially.

The regulating means of the control means for moving the slide block 103 is identical with or analogous to the regulating means described in'connection with FIG. 3. Each of the housings 1, 100 may receive two or more displacing pistons for the respective slide block. 11,

103. i I i FIG. 6 illustrates a twin radial piston machine which comprises two mirror symmetrical units 120 and 121.

The two units comprise a common shaft 122.corresponding to the shaft 19 of FIG. 1. The disk-shaped flange-123 of the shaft v122 is'connected with the cylinder ,blocks (not specifically shown) of both units. It. is preferred to provide the flange 123 with torque trans-- mitting claws 123a which enter complementary recesses or sockets of the cylinder blocks, or vice versa. The housings of the units 120 and 121 haveflanges 120a, 121a which are pivotally connected to each other by means of one or more hinges 124 and are normally fixedly secured to each other by means of screwsg125 or analogous fasteners. Otherwise, the construction of each of the units 120, 121 is the same as described in connection with FIGS. 14 or FIG. 5., When the fasteners125 are removed,- the unit 121 can be pivoted about the pintle of the hinge 124 to a position. in which an attendant can gain access tothe interior of each unit for the purposes of .inspection,

v.cleaning, repair and/or replacement of parts. In such position of.the unit 121, the flange 123is disconnected from the cylinder block of the unit 121 but remains coupled to the cylinder block of the unit 120.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for .various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to .the art and, therefore, such adaptations should and are intended to be comprehended within the. meaning and range of equivalence of the claims.

What is claimed as newand desired to be protected by Letters Patent is set forth in the appendednclaims:

1. In an arrangement including at least one radial piston machine, a combination comprising a housing; a cylinder block rotatably mounted in said housing and having a plurality of radial cylinder bores; pistons reciprocably installed in said cylinder bores and extending radially outwardly from said cylinder block; an an-- nular slide block surrounding said cylinder block in said housing and being engaged by said pistons said slide'block having an end face provided with an endless groove and being movable substantially radially of said cylinderblock to thereby change the strokes of said pistons; and control means for movingsaid'slide. block relative to said cylinder block, including at least one displacing piston axially movable in said housing in substantial parallelism with said end face of said slide having a plurality of radial cylinder bores; pistons reciprocably installed in said cylinder bores and extending radially outwardly from said cylinder block; an annular slide block surrounding said cylinder block in torque transmitting means .connecting said shaft with said cylinder block.

8. A combination as defined in claim 7, wherein said shaft comprises a flange adjacent to one axial end of arm to said displacing piston so that said lever is piv- I said housing and being engaged by said pistons, said slide block having an end face and being movable substantially radially of said cylinder block to thereby change the strokes of said pistons; a pintle secured to said housing and extending into an axialbore of said :cylinder block; a shaft rotatably .mounted in said housing and connected forrotation with said cylinderblock, said pintle having an axial bore for a portion of said shaft; andcontrol means for moving said slide block 7 relative to said cylinder block, including at least one displacing piston axially movable in said housing in substantial parallelism with said end face of said slide block, and motion transmitting means for moving said slide block relative to said cylinder block in response to axial movement of said displacing piston.

. 3. A combination as defined in claim 2, wherein said housing has an internal space for said cylinder block, said pintle and said slide block, said internal space including a recess and said pintle having a flange which. is received in said recess.

4. In an arrangement including at least one radial piston machine, acorn-bination comprising a housing; a

cylinder block rotatably mounted in said housing and having a plurality of radial cylinder bores; pistons reciprocably installed in said cylinder bores and extending radially outwardly from said cylinder block; an an- I nular slide block surrounding said cylinder block in said housing and being engaged by said pistons, said slide block having an end faceand being movable substantially radially to thereby change the strokes of said pistons; and control means for moving said slide block relative to said cylinder block, including at least one displacing piston axially movable in said housing in substantial parallelism with said end face of said slide block and motion transmitting means between said displacing piston and said slide block for positively moving said slide block relative to said cylinder block in ei ther of two diametrically opposite directions in re sponse to a corresponding axial movement of said displacing piston.

S. A combination as defined in claim 4, wherein said displacing piston is adjacent to said end face of said slide block.

6. A combination as defined in claim 4, wherein said housing is provided with two parallel internal guide surfaces and said slide block is disposed between said guide surfaces and rolls along one of said guide surfaces in response to axial movement of said displacing piston.

7. A combination as defined in claim 4, further comprising a shaft coaxial with said cylinder block and said cylinder block and said torque transmitting means comprises at least one claw provided on said flange and extending into a complementary socket of said cylinder block. v

9. A combination as defined in claim 4, wherein said motion transmitting means comprises a lever pivotably mounted in said housing and having a first arm and a second arm, means for articulately connecting said first oted in response to axial movement of said displacing piston, and entraining means coupling said second arm to said slide block so that the latter moves substantially radially of said cylinder block in response to pivoting of said lever.

10. A combination as defined in claim 9, wherein said slide block is rotatable in said housing and said entraining means comprises an element which is coupled to said slide block against radial movement but allows said slide block to rotate with respect thereto.

11. A. combination as defined in claim 4, further comprising a second housing, a second cylinderblock and a second slide block in said second housing, second pistons reciprocable in the cylinder bores of said second cylinder block, and means for articulately connecting one of said housings to the other of said housings so that said one housing is movable relative to said other housing to a position in which the interior of each of said housings is accessible.

12. A combination as defined in claim 11, further comprising a shaft rotatably mounted in said first mentioned housing and torque transmitting means connecting said shaft with said cylinder block so that said shaft rotates in response to rotation of said cylinder blocks or vice versa, said torque transmitting means being arranged to allow the cylinder block in said one housing to become disengaged from said shaft in response to movement of said one housing to said position.

13. A combination as defined in claim 11, wherein said means for articulately connecting said one housing to said other housing comprises at least one hinge.

14. A combination as; defined in claim 1, further comprising a pintle fixed to said housing and extending into an axial bore of said cylinder block, said pintle having a peripheral surface provided with a highpressure chamber and a low-pressure chamber and said cylinder bores of said cylinder block being arranged to communicate alternately with said high-pressure chamber and said low-pressure chamber in response to rotation of said cylinder block, said pintle further having first and second substantially kidney-shaped holes respectively communicating with said high-pressure chamber and said low-pressure chamber.

15. A combination as defined in claim 14, wherein each of said holes comprises a portion which is substantially paraliel'to the axis of said cylinder block.

16. A combination as defined in claim 15, wherein each of said holes is machined into said pintle in accordance with an electrochemical process. 

1. In an arrangement including at least one radial piston machine, a combination comprising a housing; a cylinder block rotatably mounted in said housing and having a plurality of radial cylinder bores; pistons reciprocably installed in said cylinder bores and extending radially outwardly from said cylinder block; an annular slide block surrounding said cylinder block in said housing and being engaged by said pistons said slide block having an end face provided with an endless groove and being movable substantially radially of said cylinder block to thereby change the strokes of said pistons; and control means for moving said slide block relative to said cylinder block, including at least one displacing piston axially movable in said housing in substantial parallelism with said end face of said slide block, and motion transmitting means for moving said slide block relative to said cylinder block in response to axial movement of said displacing piston, said motion transmitting means comprising a pin secured to said displacing piston and having a portion extending into said endless groove of said slide block.
 2. In an arrangement including at least one radial piston machine, a combination comprising a housing; a cylinder block rotatably mounted in said housing and having a plurality of radial cylinder bores; pistons reciprocably installed in said cylinder bores and extending radially outwardly from said cylinder block; an annular slide block surrounding said cylinder block in said housing and being engaged by said pistons, said slide block having an end face and being movable substantially radially of said cylinder block to thereby change the strokes of said pistons; a pintle secured to said housing and extending into an axial bore of said cylinder block; a shaft rotatably mounted in said housing and connected for rotation with said cylinder block, said pintle having an axial bore for a portion of said shaft; and control means for moving said slide block relative to said cylinder block, including at least one displacing piston axially movable in said housing in substantial parallelism with said end face of said slide block, and motion transmitting means for moving said slide block relative to said cylinder block in response to axial movement of said displacing piston.
 3. A combination as defined in claim 2, wherein said housing has an internal space for said cylinder block, said pintle and said slide block, said internal space including a recess and said pintle having a flange which is received in said recess.
 4. In an arrangement including at least one radial piston machine, a combination comprising a housing; a cylinder block rotatably mounted in said housing and having a plurality of radial cylinder bores; pistons reciprocably installed in said cylinder bores and extending radially outwardly from said cylinder block; an annular slide block surrounding said cylinder block in said housing and being engaged by said pistons, said slide block having an end face and being movable substantially radially to thereby change The strokes of said pistons; and control means for moving said slide block relative to said cylinder block, including at least one displacing piston axially movable in said housing in substantial parallelism with said end face of said slide block and motion transmitting means between said displacing piston and said slide block for positively moving said slide block relative to said cylinder block in either of two diametrically opposite directions in response to a corresponding axial movement of said displacing piston.
 5. A combination as defined in claim 4, wherein said displacing piston is adjacent to said end face of said slide block.
 6. A combination as defined in claim 4, wherein said housing is provided with two parallel internal guide surfaces and said slide block is disposed between said guide surfaces and rolls along one of said guide surfaces in response to axial movement of said displacing piston.
 7. A combination as defined in claim 4, further comprising a shaft coaxial with said cylinder block and torque transmitting means connecting said shaft with said cylinder block.
 8. A combination as defined in claim 7, wherein said shaft comprises a flange adjacent to one axial end of said cylinder block and said torque transmitting means comprises at least one claw provided on said flange and extending into a complementary socket of said cylinder block.
 9. A combination as defined in claim 4, wherein said motion transmitting means comprises a lever pivotably mounted in said housing and having a first arm and a second arm, means for articulately connecting said first arm to said displacing piston so that said lever is pivoted in response to axial movement of said displacing piston, and entraining means coupling said second arm to said slide block so that the latter moves substantially radially of said cylinder block in response to pivoting of said lever.
 10. A combination as defined in claim 9, wherein said slide block is rotatable in said housing and said entraining means comprises an element which is coupled to said slide block against radial movement but allows said slide block to rotate with respect thereto.
 11. A combination as defined in claim 4, further comprising a second housing, a second cylinder block and a second slide block in said second housing, second pistons reciprocable in the cylinder bores of said second cylinder block, and means for articulately connecting one of said housings to the other of said housings so that said one housing is movable relative to said other housing to a position in which the interior of each of said housings is accessible.
 12. A combination as defined in claim 11, further comprising a shaft rotatably mounted in said first mentioned housing and torque transmitting means connecting said shaft with said cylinder block so that said shaft rotates in response to rotation of said cylinder blocks or vice versa, said torque transmitting means being arranged to allow the cylinder block in said one housing to become disengaged from said shaft in response to movement of said one housing to said position.
 13. A combination as defined in claim 11, wherein said means for articulately connecting said one housing to said other housing comprises at least one hinge.
 14. A combination as defined in claim 1, further comprising a pintle fixed to said housing and extending into an axial bore of said cylinder block, said pintle having a peripheral surface provided with a high-pressure chamber and a low-pressure chamber and said cylinder bores of said cylinder block being arranged to communicate alternately with said high-pressure chamber and said low-pressure chamber in response to rotation of said cylinder block, said pintle further having first and second substantially kidney-shaped holes respectively communicating with said high-pressure chamber and said low-pressure chamber.
 15. A combination as defined in claim 14, wherein each of said holes comprises a portion which is substantially parAllel to the axis of said cylinder block.
 16. A combination as defined in claim 15, wherein each of said holes is machined into said pintle in accordance with an electrochemical process. 